Cell Wall Of Bacteria Research Articles

Discovery of potential natural therapeutics targeting cell wall biosynthesis in multidrug-resistant Enterococcus faecalis: a computational perspective.

Identifying therapeutic inhibitors of crucial enzymes involved in the peptidoglycan biosynthesis pathway is pivotal for developing new treatments against multidrug-resistant Enterococcus faecalis V583. MurM, an essential enzyme in this pathway, plays a significant role in the bacterium's cell wall synthesis, making it an attractive druggable target for novel antimicrobial strategies. This study explored the potential of natural compounds as inhibitors of MurM, aiming to discover promising drug candidates that could serve as the foundation for future therapeutic development. The three-dimensional structure of MurM was predicted, optimized, and its binding pocket was analyzed by comparing it with related structures. Over 4,70,000 natural compounds from the COCONUT database were subjected to virtual high-throughput screening (vHTS). The top lead candidates were selected based on their Lipinski's profile, ADME profile, toxicity profile, estimated binding free energy (ΔG) and estimated inhibition constant (Ki). Interaction pattern analysis was used to evaluate the non-covalent interactions between the inhibitors and key residues in MurM's binding pocket. Molecular dynamics simulations were performed over 300 ns to assess the structural stability and impact of these inhibitors on MurM's enzyme. Three lead compounds-CNP0056520, CNP0126952, and CNP0248480-were identified and prioritized with estimated ΔG ranging from - 9.35 to -7.9kcal/mol. Molecular dynamics simulations revealed minimal impact on MurM's overall structure and dynamics, with the candidate inhibitors forming stable protein-ligand complexes. These interactions were supported by several non-covalent interactions between the candidate inhibitors and key residues within MurM's binding pocket. These findings suggest that the identified natural product candidates could serve as promising inhibitors of MurM, potentially leading to novel therapeutics targeting cell wall biosynthesis in multidrug-resistant E. faecalis.

Cellulosic schiff base hydrogel biosensor for bacterial detection with pH/thermo-responsitivity: DFT calculations and molecular docking

A facile green hydrothermal method was developed for the preparation of fluorescent carbon dots (CDs) using sugarcane bagasse (SB) as a raw material. The incorporation of CDs within the hydroxyethyl cellulose-acrylamide hydrogel (HEC-AM) in the presence of glutardehyde (GA) as a crosslinking agent showed bright red emission under fluorescence microscope. The hydroxyethyl cellulose-N–CDs-acrylamide hydrogel (HEC-AM@N–CDs) were used as alternative biocompatible fluorescent probes for imaging and suppression of Gram-negative bacteria such as Escherichia coli (with inhibition zones 13 mm for HEC-AM to 17 mm for HEC-AM@N–CDs) &Helicobacter pylori (with inhibition zones 16 mm for HEC-AM to 13 mm for HEC-AM@N–CDs) and Gram-positive bacteria such as Micrococcus luteus (with inhibition zones 15 mm for HEC-AM to 16 mm for HEC-AM@N–CDs) &Staphylococcus aureus (with inhibition zones 13 mm for HEC-AM to 14 mm for HEC-AM@N–CDs). The N–CDs promote bacterial binding and internalization, leading to differential fluorescence emission depending on the bacteria's cell wall composition. DFT calculations support strong interactions between the bacteria and HEC-AM@N–CDs.

Thermothelomyces thermophilus cultivated with residues from the fruit pulp industry: enzyme immobilization on ionic supports of a crude cocktail with enhanced production of lichenase.

β-Glucans comprise a group of β-D-glucose polysaccharides (glucans) that occur naturally in the cell walls of bacteria, fungi, and cereals. Its degradation is catalyzed by β-glucanases, enzymes that catalyze the breakdown of β-glucan into cello-oligosaccharides and glucose. These enzymes are classified as endo-glucanases, exo-glucanases, and glucosidases according to their mechanism of action, being the lichenases (β-1,3;1,4-glucanases, EC 3.2.1.73) one of them. Hence, we aimed to enhance lichenase production by Thermothelomyces thermophilus through the application of response surface methodology, using tamarind (Tamarindus indica) and jatoba (Hymenaea courbaril) seeds as carbon sources. The crude extract was immobilized, with a focus on improving lichenase activity, using various ionic supports, including MANAE (monoamine-N-aminoethyl), DEAE (diethylaminoethyl)-cellulose, CM (carboxymethyl)-cellulose, and PEI (polyethyleneimine)-agarose. Regarding lichenase, the optimal conditions yielding the highest activity were determined as 1.5% tamarind seeds, cultivation at 50°C under static conditions for 72h. Moreover, transitioning from Erlenmeyer flasks to a bioreactor proved pivotal, resulting in a 2.21-fold increase in activity. Biochemical characterization revealed an optimum temperature of 50°C and pH of 6.5. However, sustained stability at varying pH and temperature levels was challenging, underscoring the necessity of immobilizing lichenase on ionic supports. Notably, CM-cellulose emerged as the most effective immobilization medium, exhibiting an activity of 1.01 U/g of the derivative (enzyme plus support), marking a substantial enhancement. This study marks the first lichenase immobilization on these chemical supports in existing literature.

Deleterious Effects of Histidine Tagging to the SH3b Cell Wall-Binding Domain on Recombinant Endolysin Activity.

Natural and artificial endolysins exhibit bactericidal effects by destroying peptidoglycans in the cell wall of gram-positive bacteria and are usually composed of an N-terminal catalytic domain (CTD) and a C-terminal cell wall-binding domain (CBD). The structures and receptors of CBDs are variable, but bacterial Src homology 3 (SH3b) CBDs are prevalent among the natural endolysins of Staphylococcus aureus. Moreover, although recombinant endolysins with a C-terminal 6-histidine tag (His-tag) are often produced and convenient to purify, the deleterious effects of His-tags on antibacterial activity have not been evaluated thoroughly. Recently, we reported that the antibacterial activity of a commercial lysostaphin without a His-tag differed from that of cell-free lysostaphin with a C-terminal His-tag, and lysostaphin also contains a C-terminal SH3b CBD. In this study, we directly compared the effects of His-tags on the antibacterial activities of lysostaphin and several chimeric lysins possessing different SH3b CBDs. We confirmed that antibacterial activity decreased 16.0-32.0-fold after a His-tag was added to the SH3b CBD.

Two novel antimicrobial peptides P33-57 and mP168-187 from zebrafish showing potent antibacterial activities

It is known that overuse or abuse of antibiotics has undoubtedly accelerated the global antibiotic resistance crisis, and long-time use of antibiotics may have adverse effects on the health of animal, human, and ecosystem. Therefore, it is necessary to find antibiotic alternatives that can be used in aquaculture and are non-toxic to the human. Here we clearly demonstrated that both the PH and FYVE domain of Plekhf2 in zebrafish have antibacterial properties and can interact with PGN in this study. Therefore, we screened four candidate peptides from the two domains. It was demonstrated that P152-172 and P168-187 had no obvious antibacterial activities, while P33-57 and mP168-187 had strong antibacterial activities, which may be used as antimicrobial peptides. Additionally, transmission electron microscopy experiment revealed that P33-57 and mP168-187 can destroy the cell wall of bacteria, thereby directly killing bacteria. Importantly, it was found that P33-57 and mP168-187 had no hemolysis to red blood cells and lacked cytotoxicity. In summary, P33-57 and mP168-187could be seen as antibacterial activity centers of PLEKHF2 and may be promising antimicrobial peptides to combat bacterial infections facing an antibiotic-resistance crisis.

Active packaging coating based on Lepidium sativum seed mucilage and propolis extract: Preparation, characterization, application and modeling the preservation of buffalo meat.

Buffalo meat is naturally perishable, making it susceptible to spoilage due to its high moisture content and vulnerability to microbial contamination. Edible coatings have attracted attention as a packaging method that can prolong the shelf life of meat. The study aimed to examine the impact of a combination of Lepidium sativum mucilage (LS) coating and propolis extract (PE) on prolonging the shelf life of buffalo meat. The chemical characteristics (chemical compounds, total phenol content (TPC), total flavonoid content (TFC), antioxidant activity, and cytotoxicity) and antimicrobial activity of the PE (disk diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration) were investigated. The effect of the PE on the cell wall of pathogenic bacteria was examined using a scanning electron microscope. Biological properties of LS (TPC, TFC, antioxidant activity and antimicrobial effect (pour plate method)) was investigated. Different concentrations of PE (0, 0.5, 1.5, and 2.5%) were added to the coating mixture containing LS, and their effects on extending the shelf life of buffalo meat samples stored at 4°C for 9 days were assessed. The PE included gallic acid, benzoic acid, syringic acid, 4-3 dimethoxy cinnamic acid, p-coumaric acid, myricetin, caffeic acid, luteolin, chlorogenic acid, and apigenin. The PE was determined to have a TPC of 36.67 ± 0.57 mg GAE/g and a TFC of 48.02 ± 0.65 mg QE/g. The extract's radical scavenging activity ranged from 0 to 76.22% for DPPH radicals and from 0 to 50.31% for ABTS radicals. The viability of C115 HeLa cell was observed to be 94.14 μg/mL. The PE and LS, exhibited strong antimicrobial properties against pathogenic bacteria. The LS was determined to have a TPC of 15.23 ± 0.43 mg GAE/g and a TFC of 11.51± 0.61 mg QE/g. The LS was determined to have a DPPH of 429.65 ± 1.28 μg/mL and a ABTS of 403.59 ± 1.46 μg/mL. The microbiological analysis revealed that the LS+2.5%PE treatment was the most effective in inhibiting the growth of total viable count (6.23 vs. 8.00 log CFU/g), psychrotrophic bacteria count (3.71 vs. 4.73 log CFU/g), coliforms count (2.78 vs. 3.70 log CFU/g), and fungi count (2.39 vs. 3.93 log CFU/g) compared to the control sample. The addition of PE to the edible coating also demonstrated a concentration-dependent effect on preserving the moisture, pH, color, and hardness of the buffalo meat. Sensory evaluation results suggested that incorporating PE into the edible coating extended the shelf life of buffalo meat by three days. In the second stage of this paper, this investigation employed two distinct forecasting methodologies: the Radial Basis Function (RBF) and the Support Vector Machine (SVM), to predict a range of quality indicators for coated meat products. Upon comparison, the RBF model exhibited a higher level of accuracy, showcasing its exceptional capacity to closely match the experimental outcomes. Therefore, this type of food coating, renowned for its strong antimicrobial properties, has the potential to effectively package and preserve perishable and delicate food items, such as meat.

Application of artificial neural network for the mechano-bactericidal effect of bioinspired nanopatterned surfaces.

This study aimed to calculate the effect of nanopatterns' peak sharpness, width, and spacing parameters on P. aeruginosa and S. aureus cell walls by artificial neural network and finite element analysis. Elastic and creep deformation models of bacteria were developed in silico. Maximum deformation, maximum stress, and maximum strain values of the cell walls were calculated. According to the results, while the spacing of the nanopatterns is constant, it was determined that when their peaks were sharpened and their width decreased, maximum deformation, maximum stress, and maximum strain affecting the cell walls of both bacteria increased. When sharpness and width of the nano-patterns are kept constant and the spacing is increased, maximum deformation, maximum stress, and maximum strain in P. aeruginosa cell walls increase, but a decrease in S. aureus was observed. This study proves that changes in the geometric structures of nanopatterned surfaces can show different effects on different bacteria.

Peptidoglycan-Chi3l1 interaction shapes gut microbiota in intestinal mucus layer

The balanced gut microbiota in intestinal mucus layer plays an instrumental role in the health of the host. However, the mechanisms by which the host regulates microbial communities in the mucus layer remain largely unknown. Here, we discovered that the host regulates bacterial colonization in the gut mucus layer by producing a protein called Chitinase 3-like protein 1 (Chi3l1). Intestinal epithelial cells are stimulated by the gut microbiota to express Chi3l1. Once expressed, Chi3l1 is secreted into the mucus layer where it interacts with the gut microbiota, specifically through a component of bacterial cell walls called peptidoglycan. This interaction between Chi3l1 and bacteria is beneficial for the colonization of bacteria in the mucus, particularly for Gram-positive bacteria like Lactobacillus. Moreover, a deficiency of Chi3l1 leads to an imbalance in the gut microbiota, which exacerbates colitis induced by dextran sodium sulfate. By performing fecal microbiota transplantation from Villin-cre mice or replenishing Lactobacillus in IEC∆Chil1 mice, we were able to restore their colitis to the same level as that of Villin-cre mice. In summary, this study shows a ‘scaffold model’ for microbiota homeostasis by interaction between intestinal Chi3l1 and bacteria cell wall interaction, and it also highlights that an unbalanced gut microbiota in the intestinal mucus contributes to the development of colitis.

Peptidoglycan-Chi3l1 interaction shapes gut microbiota in intestinal mucus layer.

The balanced gut microbiota in intestinal mucus layer plays an instrumental role in the health of the host. However, the mechanisms by which the host regulates microbial communities in the mucus layer remain largely unknown. Here, we discovered that the host regulates bacterial colonization in the gut mucus layer by producing a protein called Chitinase 3-like protein 1 (Chi3l1). Intestinal epithelial cells are stimulated by the gut microbiota to express Chi3l1. Once expressed, Chi3l1 is secreted into the mucus layer where it interacts with the gut microbiota, specifically through a component of bacterial cell walls called peptidoglycan. This interaction between Chi3l1 and bacteria is beneficial for the colonization of bacteria in the mucus, particularly for Gram-positive bacteria like Lactobacillus. Moreover, a deficiency of Chi3l1 leads to an imbalance in the gut microbiota, which exacerbates colitis induced by dextran sodium sulfate. By performing fecal microbiota transplantation from Villin-cre mice or replenishing Lactobacillus in IEC∆Chil1 mice, we were able to restore their colitis to the same level as that of Villin-cre mice. In summary, this study shows a 'scaffold model' for microbiota homeostasis by interaction between intestinal Chi3l1 and bacteria cell wall interaction, and it also highlights that an unbalanced gut microbiota in the intestinal mucus contributes to the development of colitis.

Shapeshifting Liquid Metal Droplets Versus Superbugs

Scientists have found an exciting new way to fight a big problem called bacterial biofilms. Biofilms are made up of billions of bacteria living inside a sticky substance, a bit like a slime monster. Within biofilms, bacteria are protected from medical treatments and the human immune system. To make matters worse, biofilms are an ideal place for the emergence of new forms of bacteria with improved defenses, which are often called superbugs. Biofilms and superbugs make people very sick, and they are increasingly more difficult to treat. However, scientists may have come up with a new solution—a special liquid metal that can change shape with the help of magnets. It turns into tiny ninja-stars and spears that can pierce through the cell walls of bacteria. When this special liquid metal is exposed to a rotating magnet, the tiny stars whizz around like a whirlwind, destroying bacterial biofilm and killing the superbugs inside.

Cell shape and division septa positioning in filamentous Streptomyces require a functional cell wall glycopolymer ligase CglA.

The cell wall of monoderm bacteria consists of peptidoglycan and glycopolymers in roughly equal proportions and is crucial for cellular integrity, cell shape, and bacterial vitality. Despite the immense value of Streptomyces in biotechnology and medicine as antibiotic producers, we know very little about their cell wall biogenesis, composition, and functions. Here, we have identified the LCP-LytR_C domain protein CglA (Vnz_13690) as a key glycopolymer ligase, which specifically localizes in zones of cell wall biosynthesis in S. venezuelae. Reduced amount of glycopolymers in the cglA mutant results in enlarged vegetative hyphae and failures in FtsZ-rings formation and positioning. Consequently, division septa are misplaced leading to the formation of aberrant cell compartments, misshaped spores, and reduced cell vitality. In addition, we report our discovery that c-di-AMP signaling and decoration of the cell wall with glycopolymers are physiologically linked in Streptomyces since the deletion of cglA restores growth of the S. venezuelae disA mutant at high salt. Altogether, we have identified and characterized CglA as a novel component of cell wall biogenesis in Streptomyces, which is required for cell shape maintenance and cellular vitality in filamentous, multicellular bacteria.IMPORTANCEStreptomyces are our key producers of antibitiotics and other bioactive molecules and are, therefore, of high value for medicine and biotechnology. They proliferate by apical extension and branching of hyphae and undergo complex cell differentiation from filaments to spores during their life cycle. For both, growth and sporulation, coordinated cell wall biogenesis is crucial. However, our knowledge about cell wall biosynthesis, functions, and architecture in Streptomyces and in other Actinomycetota is still very limited. Here, we identify CglA as the key enzyme needed for the attachment of glycopolymers to the cell wall of S. venezuelae. We demonstrate that defects in the cell wall glycopolymer content result in loss of cell shape in these filamentous bacteria and show that division-competent FtsZ-rings cannot assemble properly and fail to be positioned correctly. As a consequence, cell septa placement is disturbed leading to the formation of misshaped spores with reduced viability.

Cytosolic Factors Controlling PASTA Kinase-Dependent ReoM Phosphorylation.

Bacteria adapt the biosynthesis of their envelopes to specific growth conditions and prevailing stress factors. Peptidoglycan (PG) is the major component of the cell wall in Gram-positive bacteria, where PASTA kinases play a central role in PG biosynthesis regulation. Despite their importance for growth, cell division and antibiotic resistance, the mechanisms of PASTA kinase activation are not fully understood. ReoM, a recently discovered cytosolic phosphoprotein, is one of the main substrates of the PASTA kinase PrkA in the Gram-positive human pathogen Listeria monocytogenes. Depending on its phosphorylation, ReoM controls proteolytic stability of MurA, the first enzyme in the PG biosynthesis pathway. The late cell division protein GpsB has been implicated in PASTA kinase signalling. Consistently, we show that L. monocytogenes prkA and gpsB mutants phenocopied each other. Analysis of invivo ReoM phosphorylation confirmed GpsB as an activator of PrkA leading to the description of structural features in GpsB that are important for kinase activation. We further show that ReoM phosphorylation is growth phase-dependent and that this kinetic is reliant on the protein phosphatase PrpC. ReoM phosphorylation was inhibited in mutants with defects in MurA degradation, leading to the discovery that MurA overexpression prevented ReoM phosphorylation. Overexpressed MurA must be able to bind its substrates and interact with ReoM to exert this effect, but the extracellular PASTA domains of PrkA or MurJ flippases were not required. Our results indicate that intracellular signals control ReoM phosphorylation and extend current models describing the mechanisms of PASTA kinase activation.

18F-labelled gentiobiose as potential PET-radiotracer for specific bacterial imaging: precursor synthesis, radiolabelling and in vitro evaluation.

Bacterial infections are a clinical challenge, requiring fast and specific diagnosis to ensure effective treatment. Therefore, this project is dedicated to development of positron emission tomography (PET) radiotracers specifically targeting bacteria. Unlike previously developed bacteria-specific radiotracers, which are successful in detecting Gram-negative bacteria, tracers capable of imaging Gram-positive infections are still lacking. The disaccharide gentiobiose as abundant part of the cell wall of Gram-positive bacteria could fill this gap. Herein, the synthesis and evaluation of 2'-deoxy-2'-[18F]fluorogentiobiose ([18F]FLA280) is reported. The precursor for radiolabelling was obtained from a convergent synthesis under application of a benzylidene/benzyl group protecting strategy. The first catalytic hydrogenation in 18F-radiochemistry is reported as proof of concept. The deprotection was carried out without any side product formation, giving the final radiotracer [18F]FLA280 in good radiochemical yield and excellent radiochemical purity. [18F]FLA280 was proven to be stable in murine and human blood serum for 120 minutes and was subjected to in vitro bacterial uptake studies towards S. aureus and E. coli resulting in a low bacterial uptake. The observed bacterial uptake indicates that [18F]FLA280 may be not a promising tracer candidate for in vivo translation and alternative candidates particularly for Gram-positive bacteria are required. However, further development on the concept of labelled carbohydrates and cell wall building blocks might be promising.

Magic-angle spinning NMR spectral editing of polysaccharides in whole cells using the DREAM scheme

Most bacterial, plant and fungal cells possess at their surface a protective layer called the cell wall, conferring strength, plasticity and rigidity to withstand the osmotic pressure. This molecular barrier is crucial for pathogenic microorganisms, as it protects the cell from the local environment and often constitutes the first structural component encountered in the host-pathogen interaction. In pathogenic molds and yeasts, the cell wall constitutes the main target for the development of clinically-relevant antifungal drugs. In the past decade, solid-state NMR has emerged as a powerful analytical technique to investigate the molecular organization of microbial cell walls in the context of intact cells. 13C NMR chemical shift is an exquisite source of information to identify the polysaccharides present in the cell wall, and two-dimensional 13C–13C correlation experiments provide an efficient tool to rapidly access the polysaccharide composition in whole cells. Here we investigate the use of the adiabatic DREAM (for dipolar recoupling enhancement through amplitude modulation) recoupling scheme to improve solid-state NMR analysis of polysaccharides in intact cells. We demonstrate the advantages of two-dimensional 13C–13C experiments using the DREAM recoupling scheme. We report the spectral editing of polysaccharide signals by varying the radio-frequency carrier position. We provide practical considerations for the implementation of DREAM experiments to characterize polysaccharides in whole cells. We demonstrate the approach on intact fungal cells of Neurospora crassa and Aspergillus fumigatus, a model and a pathogenic filamentous fungus, respectively. The approach could be envisioned to efficiently reduce the spectral crowding of more complex cell surfaces, such as cell wall and peptidoglycan in bacteria.

Preparation, characterization and antioxidant and anticancerous potential of Quercetin loaded β-glucan particles derived from mushroom and yeast

β-glucans are polysaccharides found in the cell walls of various fungi, bacteria and cereals. β-glucan have been found to show various kinds of anti-inflammatory, antimicrobial, antidiabetic antioxidant and anticancerous activities. In the present study, we have isolated β-glucan from the baker’s yeast Saccharomyces cerevisiae and white button mushroom Agaricus bisporus and tested their antioxidant potential and anticancerous activity against prostate cancer cell line PC3. Particles were characterized with zeta sizer and further with FTIR that confirmed that the isolated particles are β-glucan and alginate sealing made slow and sustained release of the Quercetin from the β-glucan particles. Morphological analysis of the hollow and Quercetin loaded β-glucan was performed with the SEM analysis and stability was analyzed with TGA and DSC analysis that showed the higher stability of the alginate sealed particles. Assessments of the antioxidant potential showed that Quercetin loaded particles were having higher antioxidant activity than hollow β-glucan particles. Cell viability of the PC3 cells was examined with MTT assay and it was found that Quercetin loaded alginate sealed Agaricus bisporus derived β-glucan particles were having lowest IC50. Further ROS generation was found to increase in a dose dependent manner. Apoptosis detection was carried out with Propidium iodide and AO/EtBr staining dye which showed significant death in the cells treated with higher concentration of the particles. Study showed that particles derived from both of the sources were having efficient anticancer activity and showing a dose dependent increase in cell death in PC3 cells upon treatment.

Silver Nanoparticles Loaded With Oleuropein Alleviates LPS-Induced Acute Lung Injury by Modulating the TLR4/P2X7 Receptor-Mediated Inflammation and Apoptosis in Rats.

Toll-like receptor 4 (TLR-4) ligands were initially shown to be the source of lipopolysaccharide (LPS), a gram-negative bacterium's cell wall immunostimulatory component. Oxidative stress, apoptosis, and inflammation are all potential effects of LPS treatment on the lungs. By triggering oxidative stress and inflammation, these negative effects could be avoided. Robust flavonoid oleuropein (OLE) exhibits anti-inflammatory, antiproliferative, and antioxidative properties. A nanodelivery system could improve its low bioavailability, making it more effective and useful in treating chronic human ailments. This study evaluates the effects of AgNP-loaded OLE on LPS-induced lung injury in rats in terms of TLR4/P2X7 receptor-mediated inflammation and apoptosis. Forty-eight male albino rats were randomly divided into eight groups. Drugs were administered to the groups in the doses specified as follows: Control, LPS (8 mg/kg ip), OLE (50 mg/kg) AgNPs (100 mg/kg), OLE + AgNPs (50 mg/kg), LPS + OLE (oleuropein 50 mg/kg ig + LPS 8 mg/kg ip), LPS + AgNPs (AgNPs 100 mg/kg ig + LPS 8 mg/kg ip), and LPS + OLE + AgNPs (OLE + AgNPs 50 mg/kg + LPS 8 mg/kg ip). After the applications, the rats were decapitated under appropriate conditions, and lung tissues were obtained. Oxidative stress (SOD, MDA, and GSH), and inflammation (IL-6, IL-1β, TNF-α, Nrf2, P2X7R, AKT, and TLR4) parameters were evaluated in the obtained lung tissues. Additionally, histopathology studies were performed on lung tissue samples. The data obtained were evaluated by comparison between groups. Both OLE and OLE + AgNPs showed potential in reducing oxidative stress, inflammation, and apoptosis (p < 0.05). These findings were supported by histopathological analysis, which revealed that tissue damage was reduced in OLE and OLE + AgNPs-treated groups. According to the results, LPS-induced lung injury can be reduced by using nanotechnology and producing OLE + AgNP.

Comparing Antimicrobial Effects of Heterotrigona itama Propolis from Two Regions of Malaysia Against Enterococcus faecalis

Objective: This present study aimed to determine and compare the antimicrobial properties of Malaysian propolis (MP) produced by Heterotrigona Itama from different regions of Malaysia, against E. faecalis. Methods: The propolis were obtained in Lenggong MLP (North Peninsula Malaysia) and Raub MRP - (Central Peninsula Malaysia). The antibacterial activities of the ethanolic extracts of propolis were conducted using antimicrobial susceptibility test (AST), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The effect of these extracts on the cell morphology were observed using scanning electron microscopy (SEM). Calcium hydroxide and 5% dimethyl sulfoxide (DMSO) were used as controls. Results: Statistical analysis was done using unpaired t-test to differentiate the difference of the two averages. The ethanol extracts of MLP showed higher activity compared to MRP at 50mg/ml on E. faecalis with zone of inhibition of 14.33mm and 10.00mm respectively. MIC test for MRP and MLP was 0.78125mg/ml and 3.125mg/ml respectively. Whereas the MBC value for both MRP and MLP was 12.50mg/ml and 50.00mg/ml respectively. SEM analysis showed that MP disrupted the size, cell morphology and the structure of the bacteria cell wall. Conclusion: Our study showed MRP outperformed MLP against E. faecalis via MIC, MBC and SEM. Dissimilarities of surrounding trees in Raub and Lenggong may provide the variable chemical source contributing to this contrast. Thus, these stingless bees have a very special relationship with plant resins, relying on them for the very survival of their nests.

Galactofuranans and Galactomannan of Cell Walls as Chemotaxonomic Characteristics of the Genus and Species of &lt;i&gt;Clavibacter&lt;/i&gt;

Two types of glycopolymers of different structures were found in the cell walls of type strains of two species of phytopathogenic bacteria, Clavibacter insidiosus VKM Ac-1402T and Clavibacter nebraskensis VKM Ac-1404T (family Microbacteriaceae, class Actinomycetes). The first type is represented by new, previously undescribed (1→6)-linked β-D-galactofuranans, which differ in the studied strains of the two species by the structure of side oligosaccharide chains (the structures are given in the text). The structure of the second glycopolymer, pyruvate-containing galactomannan, was identical in both strains. The results obtained in this work, together with those previously obtained, indicate that the presence of pyruvate-containing galactomannan and galactofuranans with an identical core structure and different oligosaccharide side substituents can be considered as a chemotaxonomic trait of the genus Clavibacter, and galactofuranans with di-, tri-, or tetrasaccharide substituents of different composition and structures can serve as chemotaxonomic markers of species. The data obtained expand our understanding of the structural diversity of natural glycopolymers and structural features of the bacteria cell walls of various taxa and may be of interest for taxonomic studies and studies aimed at elucidating the molecular mechanisms of interaction between bacteria and plant cells.

The function of CozE proteins is linked to lipoteichoic acid biosynthesis in Staphylococcus aureus.

Coordinated membrane and cell wall synthesis is vital for maintaining cell integrity and facilitating cell division in bacteria. However, the molecular mechanisms that underpin such coordination are poorly understood. Here we uncover the pivotal roles of the staphylococcal proteins CozEa and CozEb, members of a conserved family of membrane proteins previously implicated in bacterial cell division, in the biosynthesis of lipoteichoic acids (LTA) and maintenance of membrane homeostasis in Staphylococcus aureus. We establish that there is a synthetic lethal relationship between CozE and UgtP, the enzyme synthesizing the LTA glycolipid anchor Glc2DAG. By contrast, in cells lacking LtaA, the flippase of Glc2DAG, the essentiality of CozE proteins was alleviated, suggesting that the function of CozE proteins is linked to the synthesis and flipping of the glycolipid anchor. CozE proteins were indeed found to modulate the flipping activity of LtaA in vitro. Furthermore, CozEb was shown to control LTA polymer length and stability. Together, these findings establish CozE proteins as novel players in membrane homeostasis and LTA biosynthesis in S. aureus.IMPORTANCELipoteichoic acids are major constituents of the cell wall of Gram-positive bacteria. These anionic polymers are important virulence factors and modulators of antibiotic susceptibility in the important pathogen Staphylococcus aureus. They are also critical for maintaining cell integrity and facilitating proper cell division. In this work, we discover that a family of membrane proteins named CozE is involved in the biosynthesis of lipoteichoic acids (LTAs) in S. aureus. CozE proteins have previously been shown to affect bacterial cell division, but we here show that these proteins affect LTA length and stability, as well as the flipping of glycolipids between membrane leaflets. This new mechanism of LTA control may thus have implications for the virulence and antibiotic susceptibility of S. aureus.

Transcriptome-based network analysis reveals hub immune genes and pathways of hepatopancreas against LPS in Amphioctopus fangsiao

The hepatopancreas is the biggest digestive organ in Amphioctopus fangsiao (A. fangsiao), but also undertakes critical functions like detoxification and immune defense. Generally, pathogenic bacteria or endotoxin from the gut microbiota would be arrested and detoxified in the hepatopancreas, which could be accompanied by the inevitable immune responses. In recent years, studies related to cephalopods immune have been increasing, but the molecular mechanisms associated with the hepatopancreatic immunity are still unclear. In this study, lipopolysaccharide (LPS), a major component of the cell wall of Gram-negative bacteria, was used for imitating bacteria infection to stimulate the hepatopancreas of A. fangsiao. To investigate the immune process happened in A. fangsiao hepatopancreas, we performed transcriptome analysis of hepatopancreas tissue after LPS injection, and identified 2615 and 1943 differentially expressed genes (DEGs) at 6 and 24 h post-injection, respectively. GO and KEGG enrichment analysis showed that these DEGs were mainly involved in immune-related biological processes and signaling pathways, including ECM-receptor interaction signaling pathway, Phagosome signaling pathway, Lysosome signaling pathway, and JAK-STAT signaling pathways. The function relationships between these DEGs were further analyzed through protein-protein interaction (PPI) networks. It was found that Mtor, Mapk14 and Atm were the three top interacting DEGs under LPS stimulation. Finally, 15 hub genes involving multiple KEGG signaling pathways and PPI relationships were selected for qRT-PCR validation. In this study, for the first time we explored the molecular mechanisms associated with hepatopancreatic immunity in A. fangsiao using a PPI networks approach, and provided new insights for understanding hepatopancreatic immunity in A. fangsiao.